There is an intense debate in Canada between senior federal and provincial politicians over whether the country should follow its southern neighbour, the United States, and abandon the Kyoto protocol.

In recent months senior ministers at both national and provincial level have become increasingly critical of crucial sections of the treaty.

Jean Chretien has been critical of the current Kyoto rules

If Canada does pull out it will mark a sharp U-turn from the commitments made during the negotiations in Bonn last July, when Canada broke with the US and joined the European Union countries in a commitment to ratify the global warming treaty.

Ralph Klein, the premier of the oil-rich province Alberta, is among the most vocal opponents.

He says that meeting the Kyoto reductions in carbon emissions would cost billions of dollars and cripple Alberta's economy.

Treaty criticised

Senior members of the federal government have also been openly critical of the current Kyoto rules, including the prime minister Jean Chretien.

During meetings with European Union leaders in Spain in early May, he argued that Canada should get credits for its "clean energy" exports, such as natural gas, to the US.

"It's a unique situation," said Mr Chretien.

"We're next to the United States and we are the only one in that position to export non-polluting energy to a non-signing country that pollutes a lot. This should be recognised."

Mr Chretien said Canada would not be in a position to ratify if these issues are not clarified - a far cry from last July's commitment to sign sometime this year.

EU member states strongly oppose any more concessions.

They argue that Kyoto is designed to cut the emissions of gases believed by nearly all scientists to be causing climate change.

They want any system of credits to be kept to a minimum in order to avoid the possibility that richer countries could buy more credits instead of cutting their own production of greenhouse gases.

David MacDonald was Canada's Conservative environment minister from 1989 to 1993 (and approved the first draft of what became the Kyoto protocol in 1992), and now lectures in environmental ethics at Concordia University in Montreal.

He says the US withdrawal from Kyoto in March 2001 has "given considerable comfort" to Canadian critics of the agreement.

Public opinion

"The provincial voices weigh heavily in this country, but especially so with this federal government's tendency to be relatively passive and reactive. There hasn't been strong leadership in the federal government on this at all."

He points out that the politicians seem to be out of tune with the general public - opinion polls suggest three-quarters of Canadians want the government to ratify Kyoto.

But Professor MacDonald says the US withdrawal has only strengthened an existing trend in Canada against Kyoto. He says the lack of outspoken Kyoto supporters among politicians and bureaucrats has made it easier for critics, including those from the oil industry.

As for the impact of Canada not ratifying Kyoto? "I dread to think about it," says Professor MacDonald.

"Despite ourselves we still have a certain influence in the rest of the world, and other countries who are wavering on ratifying Kyoto may well use the justification of both the US and Canada to haul themselves out as well."

Even before the US withdrawal, Canada was trying to change the Kyoto protocol in its favour.

The US withdrawal has strengthened an existing trend in Canada against the Kyoto treaty

That successfully led to existing forests winning credits as carbon sinks, because they absorb carbon from the atmosphere. Ministers have continued to press for broader concessions.

But at a meeting of environment ministers in Banff, western Canada in April, the European Union angrily told Canada to stop asking for more lenient treatment.

Call for changes

It is clear that message has been ignored.

Mr Chretien's call for more changes came after a similar call from the industry minister Alan Rock.

In a letter leaked to the media Mr Rock said: "We must find ways to stay competitive while taking action on climate change.

"When the United States changed their position on ratifying Kyoto, it dramatically changed the playing field for Canada."

The clean energy exports proposal from Mr Chretien is echoed in an alternative programme of carbon dioxide cuts being proposed by the Alberta premier Ralph Klein.

Other oil-rich provinces including Saskatchewan and Newfoundland are likely to support him.

Only Quebec is a strong supporter of Kyoto, because 98% of its electricity comes from relatively "clean" hydro-electricity, which it also exports to the US.

A meeting of Canadian federal and provincial environment ministers in eastern Canada on 21-22 May could provide a firm indication of whether Canada really is planning to abandon Kyoto.